This invention relates to an improved changeable sign display device in which each of a plurality of panels of visual display material is sequentially displayed in a frame-like opening on one or more sides of the display device for pre-determined time intervals. More particularly, this invention relates to a display device having a spaced pair of endless roller chains threaded about a plurality of driver and idler rollers in the device with resilient means for conveniently suspending the display panels on a web mounted between the roller chains. Still more particularly, this invention relates to a one-sided or two-sided display device wherein flexible display panels are mounted on a web which is resiliently mounted between hinges on a spaced pair of endless roller chains threaded along a path through the device defined by driver and idler rollers to sequentially display the panels for predetermined time intervals.
The prior art has developed a number of devices for displaying panels containing messages or advertising. A billboard is a well-known example which suffers from the problem of readily and easily changing the display. Such devices have significant shortcomings in that changing the display panel is costly and inconvenient, and the same panel is thus continuously displayed for long periods of time.
Prior art display devices have employed various designs in order to produce a display device which can automatically change the display periodically. Such devices have included a flexible web for mounting the panel. However, the friction drive means employed in some prior art devices to advance the display panels tended to slip, causing the display to deframe, and the mounting of the flexible web tended to cause tearing and other disintegration of the web and the display panels which limited the size of the webs and panels and the useful lifetime of display material used in those devices. In addition, variations in the size of the panels of display material, which occurred due to age, temperature variation and other causes, resulted in inexact positioning and looseness in the display material which contributed to destruction of the display material and degradation in the visual quality of the display. Thus, in the prior art devices, the size of the display material was limited, the useful life of the display material was limited, and the visual quality of the display would severely degrade during extensive use.
An example of a serpentine-wound endless belt for continuously advancing a moving message in a two-sided display device is found in U.S. Pat. No. 2,867,050. In that device, a panel is slidably mounted for movement in a channel for receiving a projected image from an endless belt driven by perforations. Other devices showing a progressively revealed multi-sided display are found in U.S. Pat. No. 4,005,535 and 2,585,687.
Such devices have proved unsatisfactory for several reasons. For example, a friction belt when subjected to multiple starts and stops when indexing a display will tend to slip slightly causing a successively worsening deframing of the display. Moreover, it is difficult and inconvenient to replace the display panels in such displays.
Accordingly, it is a general problem in this art to provide a display device of the type described which includes a positive drive mechanism with a convenient means for changing panels in a sequential display device.